Abstract
We analyzed the frequency of occurrence and the spatial patterns of plant species in grassland communities ofBanska Bystrica, Slovakia. We established 5×5-m quadrats in three different sites : (1) a grassland established by seeding improved herbage plants after plowing in 1991("sown"), (2) a semi-natural grassland oversown with improved herbaceous species in 1991 ("oversown"), and (3) a semi-natural grassland that received no treatment. No fertilizers have been applied for these grasslands. Each quadrat was divided into 100 cells (50×50cm), and 50 cells were selected in a checkerboard pattern. Each cell was subdivided into four smaller cells (25×25cm), and each species found in each of the four smaller cells was recorded. We applied the beta-binomial distribution to the analysis of spatial patterns of individual species. The greatest spatial heterogeneity was found in the sown grassland where species with stolons, rhizomes and large tillers dominated. For the dominant species in the grasslands, we obtained a good fit to the beta-binomial distri bution. On average, the greatest species richness and diversity were found in the sown grassland where improved plant species and native plants co-existed under the non-fertilized condition, although cell-to-cell variation was very large ; in contrast, species richness and diversity were lowest in the semi-natural grassland. This result indicates that an understanding that sown grasslands are poorer in the species diversity than natural/semi-natural grasslands is not always adequate.
